1. Technical Field
The disclosure relates to an auxiliary power supply device and a power supply system including the auxiliary power supply device.
2. Description of Related Art
Japanese Unexamined Patent Application Publication No. 2014-150672 (JP 2014-150672 A) discloses an auxiliary power supply device that supplies electric power to a driving circuit of electric motor for electric power steering (EPS). The auxiliary power supply device described in JP 2014-150672 A includes a single auxiliary power supply that is connected to a main power supply, a charging circuit that charges the auxiliary power supply based on the main power supply, and a switching circuit (a discharging circuit) that switches a power supply state between a normal output voltage state in which electric power is supplied to the driving circuit using only the main power supply and a high output voltage state in which electric power is supplied to the driving circuit using both the main power supply and the auxiliary power supply by discharging of the auxiliary power supply.
When a high load is applied to the EPS, the switching circuit sets the power supply state to the high output voltage state. In this case, the auxiliary power supply is in a discharging state. On the other hand, when a low load is applied to the EPS, the switching circuit sets the power supply state to the normal output voltage state and charges the auxiliary power supply.